Not sure about how the run groups are laid out at VIR, but in Houston region all of those cars run together anyway. Prod, STU/L, GTL, SSB/SSC, SRX7, and ITA/B/C all run in the same run group here. Fields are fairly small- only around 20 cars or so, so that probably makes the difference.

Thus for Houston it wouldn't matter which class you ran in since you'd be on the track at the same time.

But I would try what Charlie said- give them a ring and ask if they'd make an allowance and go from there.